1. Field of the Invention
The present invention relates to the ink jet recording head of an ink jet recording apparatus. More particularly, the invention relates to an ink jet recording head that scans across a recording medium, such as a paper sheet.
2. Related Background Art
An ink jet recording apparatus is the recording apparatus of the so-called non-impact type recording apparatus, which is capable of recording at high speeds on various kinds of recording media. This apparatus is characterized in that it makes almost no noises at the time of recording. Because of this feature, the ink jet recording apparatus is widely adopted for an apparatus to serve as a printer, a word processor, a facsimile, a copying machine, and others that operate recording system.
As a typical method applicable to the ink jet recording, there is the one that uses electrothermal transducing devices to perform recording on a recording sheet by discharging fine droplets from fine discharge ports. This method is generally structured by an ink jet recording head that forms droplets, and a supply system that supplies ink to this head. The ink jet recording head that uses electrothermal transducing devices is provided with the electrothermal transducing devices in the pressurized chambers, and thermal energy is given to recording liquid by applying electric pulses, which serve as recording signals, to the electrothermal transducing devices. In this way, the pressure of bubbles is utilized for discharging recording droplets at the time of foaming of recording liquid (film boiling) generated by change of phases of the recording liquid.
Further, for an ink jet recording head, there is the one having the system that allows its ink tanks to be separated or does not allow them to be separated from the head.
FIGS. 10A and 10B are views which show the outer appearances of the conventional ink jet recording head of a system that allows its ink tanks to be separated from it. FIG. 10A is a cross-sectional view showing the principal part on the front thereof. FIG. 10B is a side view of such recording head. As shown in FIGS. 10A and 10B, the recording unit 1 comprises a recording device substrate (not shown) fixed to a base plate 3, and an ink supply member 4 connected with the recording device substrate, among some others. The wiring substrate 5 that supplies recording signals to the recording device substrate is adhesively bonded to the base plate 3. Also, a holder member 25 is provided with an ink supply path 7 for supplying ink from the ink tank when it is connected with the ink supply member 4 of the recording unit 1. For the joint portion between the ink supply path 7 and the ink tank, a filter 9 is provided to remove dust particles, bubbles, and the like in ink.
Then, the recording unit 1 and the holder member 25 are fixed by thermally caulking the caulking pin of the holder member 25 to couple it with the base plate of the recording unit 1. At this juncture, the ink supply member 4 of the recording unit 1 and the ink supply path 7 of the holder member 25 are connected by the application of sealing rubber 26 or a bonding agent (silicone sealant, for instance).
However, in accordance with the conventional ink jet recording head described above, it is necessary to connect the ink supply paths when the recording unit and holder member are coupled, which requires the provision of sealing members, adhesive bonding, or the like. In some cases, therefore, the problem may be encountered that air enters the ink relief or ink supply path or bubbles are trapped at the joint between ink supply paths, among some others.
As a result, the number of manufacturing processes is increased, together with the increased costs of parts, as well as additional inspection processes required, among other related operations that lead to producing unfavorable effect on heads costwise, and also, lead to disadvantages with respect to reliability of the head.
The present invention is designed with a view to solving the problems described above. The objectives of the invention are to simplify the structure of junction between the recording unit and holder member, thus providing an ink jet recording head at lower costs with higher reliability.
In order to achieve such objectives, the ink jet recording head of the present invention is structured by coupling the recording unit, which is provided with all the functions of discharging ink, and the holder member, which is provided only with the function of holding and fixing ink tanks. Unlike the conventional art, the recording unit is provided with all the functions of discharging ink, making it unnecessary to connect ink supply paths or the like. Consequently, there is no need for any provision of sealing members. Also, the inspection of the recording heads can be made only in accordance with the recording unit. The number of parts is made smaller for an easier manufacture. Therefore, not only the reliability of heads become higher, but also, the recording heads are provided at lower costs.